package com.example.demo.dao;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.demo.model.BookShelf;
import org.apache.ibatis.annotations.Select;

/**
 * 功能描述：
 *
 * @Author: Zhanghf
 * @Date: 2021/5/8 21:48
 */
public interface BookShelfMapper extends BaseMapper<BookShelf> {
    @Select("SELECT  DISTINCT COUNT(userid) FROM bookshelf;")
    public Integer countuser();
}
